Microcontroller ATmega328
Working voltage 5V
Input Voltage (recommended) 7-12V
Input Voltage (Limits) 6-20V
Digital I/O Connections 14 (of which 6 PWM)
Analog Input Connections 6
DC Load Capacity per I/O Connection 40 mA
DC Loadability for 3.3V Connection 50 mA
Flash Memory 32 KB ( ATmega328 ) of which 0.5 KB used by bootloader
SRAM 2 KB ( ATmega328 )
EEPROM 1 KB ( ATmega328 )
Operating frequency 16 MHz

The Arduino Uno R3 comes with a USB cable.